@Proxima: Then that's a bug that is FAR more important than any scroll bar issues.
@namida: I would totally agree with your arguments and find them convincing, were it not for the fact, that the Lix editor doesn't have scroll bars and noone complains there.
MMB for scroll should be implemented if it isn't already, but it should never be the only way to scroll for the reason namida stated.
RMB is fine if it's not being used for any context menus. Since the NL editor isn't a fullscreen app, edge scrolling probably wouldn't work very well.
Dragging with RMB is already implemented, as the NL editor doesn't feature context menus. So do you want to have MMB-scrolling in addition to that?
Zoom scroll by itself is bad, but zoom scroll is something I expect to see in anything with a zoom feature. If the zoom function works how I expect, the zoom scrolling functionality is an emergent property, so I expect that it should be possible to scroll with zooming if the UI is well designed. But it should NEVER be relied on. It's so clunky, especially over short distances (why do I have to zoom out then back in just to move the viewing area like 3 pixels?)
That's why we have RMB-dragging or the arrow keys for short distances.
Pretty much every Windows style GUI application has a scroll bar for scrolling. Lix can get away with not having one because the Lix editor UI happens to look a lot like the Lix game UI, so naturally you might consider trying to scroll the same way you would scroll in game. Actually, I've used one image editor that feels very awkward to scroll in, and I could never really put my finger on why until now - it doesn't have a scroll bar, and can only scroll by zooming (ugh) or with the MMB. Basically, the scroll bar is something useful to have that I don't realize just how much use I get out of it until it's gone.
Actually the one thing I hate about most image editors is that they don't offer a nice way to move around and rely on scroll bars (and sometimes on MMB, which is on my mouse the same as pressing the mouse wheel, which is extremely ugly). As such I almost solely rely on zoom-moving (yeah) for image editors.